In tonight's episode of
"Supernatural,"Sam and Dean continue their quest to close the gates of hell forever, as Sam pursues the second tablet trial. The first trial is already doing potentially irrevocable physical damage to Sam -- Castiel suggests that it's breaking him down on an atomic level -- so there's no telling what he's in for with his second one.

Meanwhile, Dean and Benny reunite after a revelatory visit from Naomi, but (spoiler alert!) Benny isn't the only character returning: looks like Jim Beaver is making his first appearance as Bobby since the Winchesters salted-and-burned his flask last season. Perhaps the new reaper (guest star Assaf Cohen) has something to do with Bobby's reappearance?

Real-life current events this week have an interesting tie to the latest "Supernatural" storylines. Fun fact: Italian archaeologists have discovered the remains of an ancient cave in Turkey. They believe the cave once represented the gate to hell -- the entrance to the underworld of Greek and Roman myth. According to legend, any animal that entered the vapor-filled cave would be dragged out dead, and indeed, it seems that rumors are true.

"We could see the cave's lethal properties during the excavation. Several birds died as they tried to get close to the warm opening, instantly killed by the carbon dioxide fumes," Francesco D'Andria, professor of classic archaeology at the University of Salento, tells
Discovery.